Modern injection systems for internal combustion engines in motor vehicles typically have a high-pressure fuel circuit via which the injection valves of the internal combustion engine are supplied with fuel, there being disposed in the high-pressure fuel circuit a volume control valve (VCV) which allows a specific volumetric flow of fuel to pass through as a function of the manner in which it is controlled. The volume control valve is conventionally controlled via an output stage by means of a pulse-width-modulated voltage signal whose duty factor is varied as a function of the desired degree of opening of the volume control valve. In order to regulate the control of the volume control valve the electric current flowing through the volume control valve, which represents the degree of opening of the volume control valve, is measured, for example at the end of each cycle interval of the pulse-width-modulated control signal. As a function of the thus determined actual value of the current flowing through the volume control valve or, as the case may be, of the corresponding degree of opening of the volume control valve, the duty factor of the pulse-width-modulated control signal is then varied in the course of a correcting action in order to set the desired degree of opening of the volume control valve.
What is problematic about the above-described conventional method of controlling a volume control valve is the fact that the resistance value of the system for controlling the volume control valve can vary dependent on temperature. The controller must then compensate for variations of said kind in the resistance value by means of a relatively strong controller output signal, which, given the temperature-induced variations in the resistance occurring during operation, necessitates a significant correction.